The present invention relates to a transmitting system for a disaster avoiding system for performing communication by address polling, and more particularly to a transmitting system in which a logical address of a transmission module such as a sensor or the like may be automatically set.
In general, a transmitting system such as a disaster avoiding system for performing communication by address polling is provided with a controller for supervising in an address polling manner, and a plurality of transmitting modules such as sensors connected to transmitting paths extending from the controller for executing the polling transmitting by using logical addresses set in each transmission module.
In such a transmitting system, addresses are set in advance in the transmission modules such as sensors. Accordingly, the sensors whose addresses are set are installed, a single sensor whose predetermined address is set at a predetermined place shown in the equipment drawings must be selected from the sensor groups to be installed. Otherwise, the address setting means such as dip switches or the like must be set on the site. These are made a burden on working.
In order to decrease such work, a method for automatically assigning the addresses is disclosed by various companies (Japanese Patent Publication No. 78024/1991, Japanese Patent Publication No. 3906/1994 and Japanese Patent Publication No. 40319/1995).
In a first piece of prior art disclosed in Japanese Patent Publication No. 78024/1991, a switching element in which a predetermined delay time is set is provided in each sensor. Upon turning a power source on, the sensors are connected to the transmitting paths in order for every delay time. Accordingly, this delay time is utilized for setting the logical address.
In a second piece of prior art disclosed in Japanese Patent Publication No. 3906/1994, an address memory and a switching element inserted in series in a transmitting line for the next stage are provided in each sensor. When the address is not set in the address memory, the switching element is opened, and when the address is set, the switching element is closed and the address setting is prohibited.
Furthermore, a third piece of prior art disclosed in Japanese Patent Publication No. 40319/1995, when the address set in a first address setter provided in a sensor is identical with address data from a central processing controller, the address sent from the central processing controller is set in a second address setter, and the polling is effected for supervision onward on the basis of the address set in the second address.
However, in the first prior art, since the sensors or the like are connected in order in accordance with the predetermined delay time, when any communication trouble occurs, the central processing controller keeps on sending an address set message to the sensor or the like to which the address is to be set, so that the delay time set in its terminal is over. As a result, there are cases where the two or more sensors or the like in which the address is not set are connected on the transmitting path. Under such a condition, when the address setting message is received in a plurality of sensors in which the address is not set, the same address is allotted to the plurality of the sensors or the like.
Also, in the first prior art, when the power source is turned on, the delay circuit is operated. Even if the address has already been set, if the address is lost due to the delay time circuit, the address is again allotted in the same way. Also, it is necessary to simply wait for the polling until the delay circuits all work and the switches connected in series in the transmitting line works. The first prior art suffers such problems.
Furthermore, in the second prior art, since the address is simply set, when the sensors or the like connected in the same transmitting path are connected in parallel, there is a disadvantage that the same address is allotted to these sensors.
Also, in the third prior art, the different logical addresses are automatically set, it is necessary to confirm what type of logical addresses are allotted for the installed sensors.